Design And Implementation Of Block Device Driver For Collinear Holographic Optical Storage

With the advent of the big data era,low-cost storage of ultra-large-scale cold data has become an important challenge.Optical storage has low cost,long life,green,energy-saving,and easy to store,making it very suitable for long-term storage of large-scale cold data.Coaxial holographic optical storage uses holographic multiplexing to store data,which can greatly increase storage density,and use two-dimensional data pages to access data.In order to enable the host to achieve a data read and write throughput rate of 1GB/s,it is necessary Design a high-speed holographic storage data channel.In response to the high-speed access requirements of holographic storage,a holographic storage data channel framework is designed.At present,the server host is used as the drive controller of the coaxial holographic optical storage to realize the common block device interface-Small Computer System Interface(SCSI)device End target,and connect multiple initiators through the network SCSI interface(SCSI over internet,i SCSI)to support remote server access through standard block device interface.Design and implement the holographic storage block device driver,convert the upper-level read and write requests into access to the back-end optical storage medium,and support the memory and hard disk analog holographic optical storage,which can be debugged and verified.In order to adapt to the parallel access of multiple read-write heads of coaxial holographic optical discs,a block device multi-queue request processing mechanism based on blk-mq(Block-Multiqueue,blk-mq for short)is designed and implemented to improve the concurrency of IO and reduce the overhead of lock contention.And reduce Cache pollution.In order to simulate the movement of the optical disc by the robotic arm,the optical disc insertion and removal function has also been added.In order to increase the flexibility of the system,the system can also respond to commands sent by the linux system call.The prototype of the holographic storage channel was realized and tested.The experimental results can realize the function of the i SCSI target,and its IO throughput rate is about 1082.625MB/s.It can support 4-way concurrency,and its aggregate throughput rate is about 1820.5MB/s.